1. Technical Field
This invention generally relates to a system and method for inspecting a sheet, and more specifically relates to a system and method for inspecting a pattern on a green sheet.
2. Background Art
Chip carriers typically include several layered sheets, and each sheet includes a ceramic having a pattern formed thereon. In one example, the ceramic is silicate and the pattern material is molybdenum. A method of forming such a sheet typically includes forming the silicate; applying, or screening, a molybdenum paste to the silicate, thereby forming the pattern on the silicate; and allowing the sheet to cure. Before the sheet cures, it is typically called a green sheet.
The pattern is often formed on only one side of the sheet. However, the ceramic often includes holes punched therein with the pattern material filling the punched holes. In this way, when the chip carrier is formed, the pattern on one sheet is connected to the pattern on another sheet via the pattern material in one or more punched holes extending between the patterns.
Patterns formed on green sheets sometimes have flaws. For example, the pattern may include a gap, or it may be smeared. Accordingly, after applying the pattern to the green sheet, it is often desirable to inspect the pattern. In fact, the pattern may be inspected several times during the process of applying it. In prior inspection systems, the green sheet was supported on a wire mesh while the pattern was inspected. However, the wire mesh support was problematic because it often damaged the green sheet, such as by smearing the pattern.